An IV injection is when a syringe is used to push the fluid into the vein. It's like a shot, but it goes directly into the vein instead of into a muscle. An IV drip is when the needle or tubing is left in the vein, and an IV bag is hung up. The fluid from the bag literally drips into the IV tubing one drop at a time, at a rate set by the doctor or nurse. Instead of being pushed into the vein by a person at a fast rate, like an injection, the only force "pushing" it into the vein is gravity. In a hospital, patients often have IV drips of saline, so they don't get dehydrated. When medicine needs to be delivered by IV, it might be injected via the same tubing the patient already has for the saline drip.

An IV drip ( also called infusion) is different from an IV injection by the length of time it takes to complete the task.